Arc tube mount and component therefor



Nov. 16,1965 R, F. HAsELL ETAL ARC TUBE MOUNT AND COMPONENT THEREFOR Filed Deo. 6, 1962 FIG. 2.

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United States Patent O 3,218,495 ARC TUBE MUNT AND COMPONENT THEREFUR Richard F. Haseli, Bloomfield, and Joseph R. Ardizzone,

West Grange, NJ., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Penn- Sylvania Filed Dec. 6, 1962, Ser. No. 242,672 Claims. (Cl. B13-25) This invention relates to electric lamps and has particular reference to an improved mount structured for supporting an arc tube Within a high-pressure gaseous discharge lamp.

High-pressure gaseous discharge lamps as presently manufactured comprise an inner arc tube that is supported Within an outer protective envelope. Such lamps are well known and are described in U.S. Patent No. 2,748,303 issued May 29, 1956, to L. Thorington.

Among the most expensive and troublesome items to make and assemble in manufacturing such lamps is the mount or supporting structure which holds the arc tube in place within the outer envelope. In order to reduce the labor and material costs of this structure various types of support members have been developed eliminating unnecessary parts and operations. While these designs were improvements over the more complicated and costly structures used previously, further reductions in both the amount of material and labor required to make the support member and mount assembly would be highly desirable.

It is accordingly the general object of the present invention to provide an electric discharge lamp having a mount structure that is cheaper and easier to make and assemble than the structures used heretofore.

Another object is the provision of an arc tube mount for a high-pressure gaseous discharge lamp which can be automatically fabricated and decreases the manufacturing costs of the lamp Without impairing its performance or quality.

Still another object of the invention is the provision of an improved support member for an arc tube or the like that is rugged, simple and economical to fabricate, and can be assembled with the arc tube by automated means.

The foregoing objects and other advantages that Will occur to those skilled in the art are achieved in accordance with the present invention by forming the arc tube support from a single piece of stiff wire that is bent into a yoke-like member having two loop portions that are shaped and spaced to receive the press seals at each I end of the arc tube. The loop-forming portions of the support member are so constructed that each loop can be locked in encircling relationship with the respective press seals by a single weld.

The combination of the foregoing yoke-like support with a press seal having properly oriented protuberances in its pressed surfaces is an important feature of the present invention since it affords the additional advantage of spacing the loop portions of the support from the ends of the arc chamber defined by the arc tube, and also from those portions of the press seals in which the lead-in conductors are embedded. This arrangement minimizes the cooling effect of the support member on the ends of the arc chamber, which can be an important factor in discharge lamps containing preselected additives, and also provides additional protection against devitrification of the arc tube around the lead-in conductor or conductors due to potential differences between them and the support member.

A better understanding of the invention will be ob- 3,2l8g495' Patented Nov. 16, 1965 ice tained by referring to the accompanying drawing, where- FIGURE l is an elevational View of a high-pressure gaseous discharge lamp embodying the present inventtion, a major portion of the outer envelope being broken away to expose the improved arc tube mount structure and supporting member;

FIG. 2 is a sectional view through the lamp taken along the reference line II-II of FIG. l, in the direction of the arrows;

FIG. 3 is an elevational view of the support yoke shown in the preceding figures;

FIG. 4 is a top plan view of the support yoke as viewed along the reference line IV-IV of FIG. 3, in the direction of the arrows;

FIG. 5 is a sectional view through the upper portionl of the support yoke taken along the line V-V of FIG. 3 in the direction of the arrows, and illustrates the first step in assembling the yoke with the arc tube (shown in dotted outline);

FIG. 6 is a similar view illustrating the final step in the assembly operation;

FIG. 7 is an elevational View of the completed arc tube-support yoke module according to the present invention;

FIG. 8 is an enlarged cross-sectional view through one of the press seals and the associated interlocked loop portion of the support yoke taken along the line VIII- VIII of FIG. 7; and

FIGS. 9 and l0 are sectional views through the upper portion of another form of support yoke illustrating the manner in which the yoke isassernbled with the arc tube in accordance with this embodiment of the invention.

While the improved support structure and member of the present invention can be used with advantage in various types of electrical devices to mount an elongated component within an envelope or the like, it is especially adapted for use in supporting the arc tube of a highpressure discharge lamp within the outer envelope and has, accordingly, been so illustrated and will be so described.

Mount structure Referring to the drawing, in FIG. l there is shown a 400 watt high-pressure mercury discharge (HPMV) lamp 11 comprising an outer envelope 12 that is fabricated from either hard or soft glass and has a bulbous intermediate portion which encloses an axially extending arc tube 14. The envelope is terminated at one end by a cylindrical dome portion 16 and at its opposite end by a cylindrical neck portion 18 that is sealed to the usual re-entrant stem 20. The arc tube 14 has a press seal 15 at each end and is held in place Within the outer envelope 12 by means of a support member such as a yoke 22 that is fabricated from a single piece of stiff wire.

As shown more particularly in FIG. 3, the support yoke 22 comprises a substantially straight shaft portion 24 that is terminated at each end by transversely extending retroverted loop-forming portions 26 and 28. These loop portions project from the same side of the shaft portion and are disposed in approximately parallel planes that are substantially normal to the shaft portion. The ends of the yoke 22 are bent to provide generally L- shaped end sections or legs 30 and 32. The leg 32 comprises the upper end of the yoke and its free end is bent to form a downwardly extending tongue, as shown.

Returning to FIG. l, the loop-forming portions 26 and 28 of the support yoke 22 encircle the press seals 15 of the arc tube I4 and are locked in such relationship by welding the mouths or terminal portions of the loops closed at points A and B. The arc tube 14 and support yoke 22 are thus securely interlocked one with another and form an integral subassembly or arc tube-support yoke module 34, as shown in FIGS. l and 7. The lowermost leg 30 of the yoke is attached, as by welding, to a rigid lead wire 35 (see FIG. 1) `sealed through the stem 20. The oppositely disposed leg 32 is provided with laterally-extending spring members 36 and 37 which resiliently engage the dome portion 16 of the outer envelope 12 and thus securely anchor the arc tube-support yoke module 34 in the desired coaxial position within the outer envelope, as shown in FIG. 2.

The inner arc tube 14 is made of quartz or the like and contains a pair of main electrodes 38 and 40 that are anchored in the press seals 15. In the particular embodiment of the invention illustrated in the drawing, the press seals 15 are of the type that extend for the full width of the arc tube 14 and have raised portions or protuberances 17 and 19 that extend longitudinally along the sides of the seal inwardly to a point located a considerable distance from the arcuate end of the arc chamber defined by the arc tube, as shown in FIGS. l and 7. The tightly compressed portions of the press seals 15 are, accordingly, of generally Y-shaped configuration and each of the pressed surfaces of the seals are provided with a pair of spaced longitudinally-extending protuberances 17 and 19 (see FIG. 8). Full press seals of this type are described in detail in U.S. Patent No. 3,025,426 issued March 13, 1962, to F. I. Camarata and entitled Press Seal.

As shown in FIG. 1, the main electrode 38 at the stem end of the lamp 11 is connected to a lead-in conductor assembly 39 that is embedded in a medial portion of the press seal and this assembly is, in turn, connected by a flexible conductor 39 to a second rigid lead wire 36 sealed through the stem 20. The oppositely disposed main electrode 40 is connected to upper leg 32 of the support yoke 22 by means of another lead-in conductor assembly 41 and flexible conductor 41. An auxiliary starting electrode 42 positioned adjacent the main electrode 38 is also anchored in the press seal 15 located at the stem end of the lamp and is connected by means of a third lead-in conductor assembly and flexible lead combination 43 to a starting resistor 44 that is electrically connected to the yoke 22. The main electrodes are of the thermionic type and the arc tube 14 contains the usual filling of mercury and an ionizable starting gas such as argon.

As shown in FIGS. 1 and 7, the shaft portion 24 of the support yoke 22 extends substantially parallel to and along one side of the arc tube 14. The shaft portion is also located further from the arc tube than the welded terminal portions or mouths of the loops 26 and 28 so as to minimize the shadow effect produced by the shaft portion when the lamp is operated.

As shown more particularly in FIGS. 2 and 3, the loop portions 26 and 28 are formed by bending selected intermediate portions of the wire yoke 22 through a right angle and then back upon itself and through a second right angle at a point located a predetermined distance from the connecting shaft portion 24. The loops are spaced longitudinally from each other a distance such that they receive the portions of the press seals 15 which have the protuberances 17 and 19 and are located beyond the end of the arc chamber dened by the arc tube 14.

As shown in FIG. 4, each of the loop portions 26 and 28 are initially open and the loop segments spread apart sufiiciently to define a predetermined angle u, such as an angle of approximately in the case of the 400 watt lamp here shown.

Method of assembly Assembly of the arc tube 14 and the support yoke 22 is achieved by simply inserting the arc tube into the open loops until each of the press seals 15 seat against the bend of the respective loops and also against the straight loop segment that lies in the same plane as the shaft portion 24, as shown in FIG. 5. The closable segments of the loops (that is, those facing the observer when the yoke 22 is oriented and viewed as shown in FIG. 3), and the respective adjoined leg portions 30 land 32 are then each swung as a unit toward the arc tube until the terminal portions of the loops seat one against the other, whereupon the abutting parts of the loops are spot welded by a pair of welding jaws 46 and 43, as shown in FIG. 6. The two components lare thus securely locked together by welds at points A and B to form the unitary arc tubesupport yoke subassembly or module 34 illustrated in FIG. 7.

An important feature of this invention is the special configuration and orientation of the closable segments of the loops 26 and 28 which permit the latter to be tightly closed around the press seals 15 without cracking them. As shown most clearly in FIG. 3, the aforesaid closable segments are slightly offset toward one another so that the terminal portions 27 and 29 thereof are displaced inwardly a predetermined distance X toward the mounting space defined by the loops 26 and 28, as for example a distance of approximately two millimeters in the particular case of the 400 watt HPMV lamp here illustrated.

In addition, these terminal portions 27 and 29 are bent through a predetermined angle ,8, such as an angle of about 46, toward the yoke proper at a point adjacent the respective legs 30 and 32, as shown in FIG. 4. This inward flaring and off-setting of the closable segments of the loops causes the adjoining sections of the legs to seat automatically against the oppositely disposed loop segments when the loops are closed around the seals `and enables the spot welding operation to be performed. If the aforesaid segments were not displaced or prebent in this manner, the bend which joins the loop portions 26 and 28 to the respective legs 30 and 32 would have to be bent around the edge of the press seal and then spot welded to the other loop segment, which operation would obviously be very difficult, if not impossible, to perform without cracking the seals.

After the arc tube 14 and support yoke 22 are coupled together, the starting resistor 44 and various liexible conductors are spot welded to the yoke and the lead-in conductor assemblies to complete the mount in the regular manner.

Additional features Experience has shown that the clamping pressure exerted on the loops 26 and 28 by the by the welding jaws 46 and 48 during assembly causes the loops to compressively grip the press seals 15, as indicated by the slightly convex or bowed configuration of the loop segments illustrated in FIG. 8. It will also be noted that the loops engage and are seated against the spaced protuberances 17 and 19 that extend along the sides of the press seals. The loops, accordingly, make essentially only point contact with the press seals and thus span, and are physically isolated from, the medial portions thereof in which the lead-in conductor assemblies 39, 41 and 43 are embedded. This provides a built-in safeguard, so to speak, against the danger that the portion of the seal surrounding the lead-in assembly 39 will gradually devitrify due to the potential difference existing between the loop 26 and the main electrode 38 when the larnp is energized.

As will be noted in FIGS. 1 and 7, the loops 26 and 28 are also physically isolated from the ends of the arc chamber defined by the arc tube 14. This spacing, coupled with the aforementioned point-contact between the yoke and press seals, drastically reduces the cooling effect of the support yoke 22 on the ends of the arc tube 14, which factor is important when selected additives (such as sodium or thallium iodide) are placed into the arc tube together with the mercury charge in order to increase the luminous output of the lamp.

Alternative embodiment It has been found that the fabrication of the support yoke can be simplified by using a modified yoke 22a of the type shown in FIGS. 9 and 10. As illustrated in FIG. 9, the loop segment 28a joined to the shaft portion 24a (rather than to the leg portions 30 and 32 as in the embodiment shown in the previous figures, and especially FIGS. 4 and 5) is bent through a predetermined angle and toward the other loop segment at a point spaced from the loop bend a distance substantially equal to the Width of the press seal 15. This forms an angled terminal portion 50 at the mouth of each of the loops. The loop segments 28a adjoined to the leg portions 39a (not shown) and 32a are left straight. The bend is, accordingly, located near the center of the respective loop segments rather than at the ends thereof, as in the above-described embodiment, and are much easier to form.

Assembly of the modified yoke 22a with the arc tube 14 is achieved in essentially the same manner as before except that each of the press seals 15 is seated against the straight loop segments 28a that adjoin the leg portion 30a and 32a, as shown in FIG. 9. The oppositely-disposed bent loop segments 23a are then swung as a unit, along with the connecting shaft portion 24a, toward the seals until the bent terminal portions 50 seat against the respective leg portions, as shown in FIG. l0. The abutting parts are then Welded together at point A by means of the Welding jaws 46 and 48.

The angle ry in the case of the 400 Watt lamp here shown is preferably the same as angle a, that is, about so that the bent terminal portions 50 are initially substantially parallel to the straight segments of the loops (see FIG. 9). Also, the welding jaws 46 and 48 are preferably tilted at a slight angle so as to seat flush against the bent terminal portions 50 as shown.

Summary It Will be appreciated from the foregoing that the objects of the invention have been achieved by providing an improved mount and support structure for an electric discharge lamp which requires a minimum of material and assembly operations. Moreover, the one-piece yoke support is so constructed that even if one or both of the Welds closing the loops Were to fail the inherent rigidity of the loops would continue to securely hold the arc tube in position Within the lamp. The novel concept of looping portions of the support member around the press seals affords the additional advantage of physically isolating the support structure from portions of the arc tube that enclose lead-in conductors or which preferably operate at an elevated temperature, as in certain additive-containing gaseous discharge lamps.

While the invention has been described with reference to a specific lamp embodiment, various changes in the conguration and arrangement of parts may be made without departing from the spirit or scope of the invention. For example, the coniiguration of the loop-forming portions of the support member can be readily modified to receive press seals that are of cylindrical configuration etc. rather than flat.

We claim:

1. A mount for a high-pressure gaseous discharge lamp comprising, in combination;

an arc tube having a press seal at each end,

a vitreous stem having a pair of lead Wires sealed therethrough, and

a support yoke fastened to one of said lead wires and holding said arc tube in predetermined spaced relationship with respect to said stern,

said support yoke comprising a bent piece of stiff wire having (a) a single shaft portion that is spaced from and extends along one side of said arc tube, and (b) transversely extending retroverted segments that are located at each end of said shaft portion and define a pair of loop portions which encircle the 6 press seals of said arc tube, each of said loop portions having an inwardly-bent terminal segment at its mouth which compressively locks the press seals in the respective loop portions.

2. A mount for a high-pressure gaseous discharge lamp as set forth in claim 4 wherein;

said arc tube is supported in substantially coaxial relationship with said stem,

the shaft portion of said support yoke is substantially straight and extends parallel to said arc tube,

the loop portions of said support yoke extend at substantially right angles to said shaft portion, and

the inwardly-bent terminal segments of said loop por tions are joined to oppositely disposed parts of the support yoke by welds.

3. An integral subassembly for a gaseous discharge lamp comprising, in combination;

an arc tube terminated at each end by a press seal having a pressed surface with spaced protuberances therein, and

support means for said arc tube comprising a bent piece of stiff wire that is spaced from and extends along one side of said arc tube and includes a pair of spaced transversely-extending loops that encircle and are tightly closed around the portions of said press seals having said protuberances,

said loops being seated against said protuberances and,

by virtue of the stiffness of said wire, thereby spanning preselected portions of said press seals and being physically isolated therefrom.

4. An integral subassembly for a gaseous discharge lamp as set forth in claim 6 wherein,

the protuberances in the pressed surfaces of said press seals are located at and extend along the sides of the seals,

said arc tube contains an electrode that is connected to said support wire by a lead-in conductor that is embedded in and extends through the medial portion of one of said press seals, and, the loop portions of said support wire engage the protuberances of the respective press seals at points remote from the arc chamber dened by said arc tube so that said loop portions are spaced from the end of said arc chamber and from the medial portion of the press seal in which the aforesaid lead-in conductor is embedded. 5. A support member for an arc tube having a seal at each end, said support member comprising a yoke that is fabricated from a single piece of stiff wire and consists of a single shaft portion and a pair of open loop portions which extend transversely from the same side of and are joined by said shaft portion, said loop portions being longitudinally spaced to receive the seals of said arc tube, and each of said loop portions having a closable segment that is bent through a predetermined angle toward the yoke proper at a point adjacent the mouth of the loop such that said closable segments seat against the oppositely disposed terminal segments of the respective loop portion when said loop portions are closed.

6. An arc tube supporting yoke as set forth in claim 5 wherein;

said shaft portion is substantially straight, said loop portions lie in approximately parallel planes that are substantially normal to said shaft portion,

said yoke includes end sections that are joined to and extend longitudinally beyond said loop portions, and the closable segments of said loop portions are offset toward the arc tube mounting space between said loop portions such that said end sections overlie and seat against the oppositely disposed terminal segments of the respective loop portions when said loop portions are closed.

7. The combination comprising,

a vitreous arc tube for an electric discharge lamp,

a press seal at one end of said arc tube having a pair of spaced protuberances on one of its pressed faces, and

a support structure fastened to said arc tube by a transversely extending rigid member that encircles the press seal and is seated in point-contact with the protuberances thereof and thus spans and is isolated from the portion of the press seal located between said protuberances.

8. In a high-pressure gaseous discharge lamp having an outer envelope that is closed at one end by a stem, the combination of;

a vitreous arc tube having a press seal at each end,

and

support means carried by said stem and holding said arc tube in predetermined position Within said outer envelope,

said support means comprising a single piece of stiff wire having (a) a single shaft portion that is spaced from and extends along one side of said arc tube, and (b) retroverted segments which define a pair of spaced loop portions that protrude from said shaft portion toward said arc tube and extend around the press seals thereof,

each of said loop portions having an inwardly-bent terminal segment at its mouth that tightly closes the respective loop portions around the press seals and thus securely locks the arc tube in said wire support.

9. The combination set forth in claim 8 wherein:

the wire support is terminated by end sections that eX- tend longitudinally beyond the respective loop portions and away from the press seals locked therein,

the retroverted segments which adjoin the respective inwardly-bent terminal segments are offset toward one another, and

the retroverted segments that are located opposite the respective end sections are seated against the parts of said end sections that adjoin the respective loop portions.

10. The combination set forth in claim 8 wherein;

the wire support is terminated by end sections that extend longitudinally beyond the respective loop portions and away from the press seals locked therein, and

the inwardly-bent terminal segments of the respective loop portions overlie the associated end sections and are joined thereto by welds.

References Cited by the Examiner UNITED STATES PATENTS 2,103,029 12/ 1937 Davies 313-25 X 2,802,961 8/1957 Jenne 313-25 2,918,592 12/ 1959 Pomfrett et al S13-184 X 3,025,426 3/1962 Camarata 313--184 GEORGE N. WESTBY, Primary Examiner. 

7. THE COMBINATION COMPRISING, A VITREOUS ARC TUBE FOR AN ELECTRIC DISCHARGE LAMP, A PRESS SEAL AT ONE END OF SAID ARC TUBE HAVING A PAIR OF SPACED PROTUBERANCES ON ONE OF ITS PRESSED FACES, AND A SUPPORT STRUCTURE FASTENED TO SAID ARC TUBE BY A TRANSVERSELY EXTENDING RIGID MEMBER THAT ENCIRCLES THE PRESS SEAL AND IS SEATED IN POINT-CONTACT WITH THE PRO- 